title: The A3 allele of the HLA-DQA1 locus is associated with susceptibility to type 1 diabetes in Japanese.
abstract: Analysis of the frequencies of class II HLA-DR and HLA-DQ alleles by serological and DNA typing in 49 Japanese patients with type 1 (insulin-dependent) diabetes and 31 Japanese controls indicates the following. (i) Susceptibility is more strongly associated with the HLA-DQ subregion than with the HLA-DR subregion. (ii) Of the class II alleles detected, the A3 allele of the DQA1 locus was the most strongly associated with disease. Ninety-six percent of the patients were positive for the A3 allele compared to 53% of the controls (P = 0.001; relative risk = 19.7; confidence limits = 3.72-188.64). (iii) The DQw8 allele of the DQB1 locus, which is associated with susceptibility to type 1 diabetes in Caucasians and Blacks, was not increased in frequency in Japanese patients (22%) versus controls (19%). (iv) Asp-57-encoding DQB1 alleles are associated with reduced susceptibility to type 1 diabetes in Caucasians. The major predisposing haplotypes in Japanese are DR4 and DR9. By DNA sequence analysis, both of these Japanese haplotypes have Asp-57-encoding DQB1 alleles. Oligonucleotide dot blot analysis showed that all, except 1, of the 49 Japanese patients and all of the 31 controls have at least one Asp-57-encoding DQB1 allele. In addition, 40% of the patients were homozygous for Asp-57-encoding DQB1 alleles versus 35% of the controls. The high frequencies of Asp-57-encoding DQB1 alleles in this ethnic group may account for the rarity of type 1 diabetes in Japan.
authors.affiliation: Nuffield Department of Surgery, John Radcliffe Hospital, Headington, Oxford, United Kingdom.
authors.forename: J A
authors.initials: JA
authors.lastname: Todd
authors.forename: Y
authors.initials: Y
authors.lastname: Fukui
authors.forename: T
authors.initials: T
authors.lastname: Kitagawa
authors.forename: T
authors.initials: T
authors.lastname: Sasazuki
mesh_terms: D000483:Alleles; D001483:Base Sequence; D003922:Diabetes Mellitus, Type 1 / Q000235:genetics* / Q000276:immunology; D004198:Disease Susceptibility; D005787:Gene Frequency; D006683:HLA-DQ Antigens / Q000235:genetics*; D059866:HLA-DQ beta-Chains; D006239:Haplotypes; D006801:Humans; D007564:Japan; D008969:Molecular Sequence Data; D015345:Oligonucleotide Probes; D016133:Polymerase Chain Reaction; D012016:Reference Values
chemical_list: D006683:HLA-DQ Antigens; D059866:HLA-DQ beta-Chains; C109756:HLA-DQ8 antigen; C057615:HLA-DQbeta antigen; D015345:Oligonucleotide Probes